RPR-12

Barrier transmission B = P d² / WUT

B = P d² / (W U T). Allowed primary-barrier transmission.

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Barrier designNCRP 151NCRP 147

Governing equation

B=P d^{2}/(WUT)

$d \in \left[1, 20\right]$

where

P: Weekly design limit (mSv/wk)
d: Distance to point (m)
W: Workload at 1 m (Gy/wk)
U: Use factor (—)
T: Occupancy (—)
B: Allowed transmission (—)

The figure, part by part

Each numbered marker wears the color of its card. Hover a card to light the marker. Tap a marker to jump to that card. The slider walks a red point along the curve; Animate drawing traces it like a pen.

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①

Governing law — red

B=P d^{2}/(WUT)

$d \in \left[1, 20\right]$

$d = 1$ $B = 8\times 10^{-8}$

Along the curve

②

Domain of the variable — blue

d_{\min} = 1,\quad d_{\max} = 20

$d \in \left[1, 20\right]$

$d = 1$ $d = 1$

Along the curve

③

Response curve — green

B=P d^{2}/(WUT)

$d \in \left[1, 20\right]$

$d = 1$ $B = 8\times 10^{-8}$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}B}{\mathrm{d}d}

$d \in \left[1, 20\right]$

$d = 1.119$ $B^{\prime} = 1.79\times 10^{-7}$

Along the curve

Lecture brief

Historical brief

Inverse-square, half-value layer, ICRP weighting and ALARA are the protection craft since the 1920s commissions. The lab computes transmission, equivalent dose and a shielding snapshot. This sheet (RPR-12 — Barrier transmission B = P d² / WUT) is the form associated with NCRP 151 · NCRP 147. Working symbols: $P$ , $d$ , $W$ , $U$ , $T$ $\rightarrow$ $B$ . P is the weekly design limit (0.02 mSv/wk public, 0.1 mSv/wk controlled). W in Gy/wk at 1 m; photons take Gy ≡ Sv.

Purpose

Purpose: compute

B

from

P

d

W

U

T

in Radiation protection via

B=P d^{2}/(WUT)

B = P d² / (W U T). Allowed primary-barrier transmission. Use it when a real radiation protection question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

P = 0.020\,\mathrm{mSv/wk}

d = 4.000\,\mathrm{m}

W = 250.000\,\mathrm{Gy/wk}

U = 1.000\,\mathrm{—}

T = 1.000\,\mathrm{—}

, the governing relation

B=P d^{2}/(WUT)

yields

B = 1.280e-6\,\mathrm{—}

. A wall, a point of interest, a tiny allowed B. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Weekly design limit P0.02 mSv/wkDistance to point d4 mWorkload at 1 m W250 Gy/wkUse factor U1 —Occupancy T1 —

Outputs

Allowed transmission B0.000001 —

Reading speed

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Narration of this film

A wall, a point of interest, a tiny allowed B.

P is the weekly design limit (0.02 mSv/wk public, 0.1 mSv/wk controlled). W in Gy/wk at 1 m; photons take Gy ≡ Sv.

Reading speed

Watch on YouTube